Polyethylene terephthalate molding compositions

ABSTRACT

Polyethylene terephthalate molding compositions are provided which comprise a polyethylene terephthalate having an inherent viscosity of at least 0.4, a plasticizer, a lubricating polymer, a nucleating agent, a reinforcing agent or mixture of reinforcing agent and filler, and a molecular weight reducing agent for the polyethylene terephthalate. The molding compositions can be injection molded utilizing mold temperatures below 100° C. (e.g, 60°-90° C.). The molded compositions exhibit an excellent balance of properties such as tensile strength, flex modulus, heat distortion temperature and impact strength.

This application is a division of application Ser. No. 391,200 filedJune 23, 1982, now U.S. Pat. No. 4,440,889.

BACKGROUND OF THE INVENTION

The invention relates to polyethylene terephthalate moldingcompositions. More particularly, the invention relates to polyethyleneterephthalate molding compositions which in addition to plasticizers,nucleating agents and reinforcing agents or mixtures thereof withfillers contain molecular weight reducing agents for the polyethyleneterephthalate.

Polyethylene terephthalate has been widely used for some time for fibersand films. However, the polymer has not yet achieved wide commercialacceptance for use as a molding material. Several factors havecontributed to the lack of commercial acceptance of this polymer for useas a molding material. The major factors relate to the slow rate ofcrystallization and lack of roughness of polyethylene terephthalate.

Thus, polyethylene terephthalate has a slow rate of crystallization ascompared to other moldable crystalline polymers. This has resulted ingreat difficulty in preparing molded articles having uniform propertiesand surface characteristics from this polymer using conventional moldingtemperatures (i.e., 70°-100° C.) and molding cycles. The use of highermolding temperatures (e.g., 130° C. or more) and longer molding cycleshave generally proven to be impractical since most conventional moldsare water heated and attain temperatures of only about 110° C. Whilethere are a few oil-heated molds which attain temperatures greater than110° C., these are generally inconvenient to use and often exhibituneven heating temperatures.

Recent approaches to the crystallization problem have involved the useof various nucleating agents to promote more rapid crystallization ofthe polyethylene terephthalate. A wide variety of nucleating agents havebeen proposed for that purpose in the prior art. Thus, U.S. Pat. No.4,305,864 describes the use of ionizable metal salts of organiccompounds having at least one acidic proton such as the sodium,potassium and lithium salts of carboxylic acids, particularlysubstituted carboxylic acids of which substituted benzoic acids arepreferred. U.S. Pat. No. 4,284,540 refers to known nucleating agentssuch as benzophenone, inorganic powders and metal soaps. U.S. Pat. No.4,172,859 refers to nucleating agents such as talc, calcium fluoride,sodium fluoride, alumina and polytetrafluoroethylene. U.S. Pat. No.3,368,995 refers to nucleating agents which include carbon powders,carbon black, oxides of the metals of Group II of the Periodic Table,sulfates such as CaSO₄ and BaSO₄, phosphates such as Ca₃ (PO₄)₂,silicates such as CaSiO₃ and MgSiO₃, oxalates such as calcium oxalates,stearates such as magnesium stearate, benzoates such as calciumbenzoates, salicylates such as zinc salicylate, talc and the neutralclays. British Patent application No. 2,015,013 refers tocrystallization promoters which include the sodium or potassium salts ofa hydrocarbon acid containing 7 to 25 carbon atoms.

The major approach to the problem of lack of toughness of thepolyethylene terephthalate has been to utilize various reinforcing andfiller materials, including a reinforcing material such as glass fibersand fillers such as mica, talc, clay and the like. Such materials aredescribed in many of the above-mentioned patents. In addition, it hasbeen proposed to improve the impact strength of polyethyleneterephthalate by the addition thereto of a wide variety of polymericmodifiers, including among others acrylic or methacrylic monomer graftedcopolymers of conjugated dienes alone or in combination with a vinylaromatic hydrocarbon or an aromatic polycarbonate resin, see U.S. Pat.No. 4,280,948 and U.S. Pat. No. 4,280,949; copolymers of alpha-olefinsand a glycidyl ester of an unsaturated aliphatic carboxylic acid, seeU.S. Pat. No. 4,284,540; and the wide variety of rubbery modifiersdescribed in U.S. Pat. No. 4,172,859.

While the polyethylene terephthalate molding compositions described inthe above-mentioned patents exhibit desirable properties, in somerespects they fail to exhibit the overall balance of properties neededin a fully acceptable molding material. Thus, commercially acceptablepolyethylene terephthalate compositions are needed which exhibit anexcellent balance of properties including high tensile strength, highflex modulus, high heat distortion temperature and good impact strength.

SUMMARY OF THE INVENTION

In accordance with the present invention, a polyethylene terephthalatemolding composition has now been developed which exhibits an excellentbalance of properties including tensile strength, flex modulus,distortion temperature and impact strength. The composition comprises:

(a) from about 40 to about 70 parts by weight per 100 parts by weight oftotal composition of a polyethylene terephthalate having an intrinsicviscosity of at least 0.4 as measured at 25° C. in a 1:1 mixture ofphenol and tetrachloroethane;

(b) from about 0.5 to about 5.0 parts by weight per 100 parts by weightof total composition of a plasticizer selected from the group consistingof benzoate esters of polyols, phthalate esters and phosphate esters;

(c) from about 0.5 to about 0.5 to 10.0 parts by weight per 100 parts byweight of total composition of a lubricating polymer;

(d) from about 0.1 to about 5.0 parts by weight by weight per 100 partsby weight of total composition of a nucleating agent;

(e) from about 20 to about 60 parts by weight per 100 parts by weight oftotal composition of a reinforcing material or mixture of reinforcingmaterial and filler; and

(f) from about 0.01 to about 1.0 parts by weight per 100 parts by weightof total composition of a molecular weight reducing agent for saidpolyethylene terephthalate, wherein said molecular weight reducing agentis selected from the group consisting of benzoic acid, neopentyl glycoland water.

DETAILED DESCRIPTION OF THE INVENTION

The polyethylene terephthalate resins employed in the compositions ofthe invention can be obtained commercially or they can be prepared byknown techniques such as by the alcoholysis of esters of terephthalicacid with ethylene glycols as described in U.S. Pat. Nos. 2,465,319 and3,047,359 and elsewhere. The polyethylene terephthalate resins employedherein will have intrinsic viscosities of at least 0.4 deciliters pergram (dl/g) and may have intrinsic viscosities of 0.4 to 1.0, preferably0.45 to 0.55 dl/g as measured in a 1:1 mixture of phenol andtetrachloroethane at 25° C. The amounts of polyethylene terephthalateutilized in the composition may range from 40 to about 70 parts byweight per 100 parts by weight of total composition. Preferred amountsare from 45 to 65 parts by weight of total composition.

As indicated, the plasticizers employed in the compositions of theinvention are selected from benzoate esters of polyols, phthalate estersand phosphate esters. Suitable benzoate esters of polyols which may beemployed include neopentyl glycol dibenzoate, triethylene glycoldibenzoate, polyethylene glycol dibenzoate, glycerol tribenzoate,pentaerythritol tetrabenzoate, dipropylene glycol dibenzoate, diethyleneglycol dibenzoate and the like. Suitable phthalate esters which may beemployed include dicyclohexyl phthalate, diphenyl phthalate, dibenzylphthalate, dioctyl phthalate, butyl benzyl phthalate and the like.Suitable phosphate esters which may be employed include tricresylphosphate, cresyl diphenyl phosphate, trixylyl phosphate and the like.The preferred plasticizers are the benzoate esters of polyols and ofthese neopentyl glycol dibenzoate is particularly preferred.

The amounts of plasticizer which may be present in the compositions mayrange from about 0.5 to about 5.0 parts by weight per 100 parts byweight of total composition. Preferred amounts are from 2.0 to 4.0 partsby weight per 100 parts by weight of total composition.

A wide variety of lubricating polymers may be utilized in thecompositions of the invention. Such polymers in addition to acting aslubricants may also serve to impart improved impact resistance to themolded composition. Suitable lubricating polymers include the sodium andzinc salts of copolymers of alpha-olefins and alpha-beta-ethylenicallyunsaturated carboxylic acids such as ethylene/acrylic acid,propylene/acrylic acid, ethylene/methacrylic acid, propylene/methacrylicacid and the like; polysiloxanes such as polydimethylsiloxane,polydiethylsiloxane and the like; polyolefins such as polyethylene,polypropylene and the like; polyethylene copolymers containing from 2-7%of epoxy groups; ethylene/alpha-olefin/diene (EPDM) copolymers such asethylene/propylene/1,4-hexadiene, ethylene/propylene/dicyclopentadiene,ethylene/propylene/5-ethylidene-2-norbornene and the like; maleicanhydride adducts of EPDM copolymers; polyamides such aspolycaprolactams, polylaurolactam, polyhexamethylene adipamide and thelike; and polymers of vinyl aromatic hydrocarbons such as polystyrene,poly-alpha-methylstyrene and the like. The preferred lubricatingpolymers are the sodium or zinc salts of copolymers of alpha-olefins andalpha-beta-ethylenically unsaturated carboxylic acids.

The amounts of lubricating polymer utilized in the molding compositionmay vary considerably depending on desired properties. Suitable amountsmay range from about 0.5 to about 10.0 parts by weight per 100 parts byweight of total composition. Preferred amounts range from 1.0 to 5.0parts by weight per 100 parts by weight of total composition.

Various nucleating agents may be utilized in the compositions of theinvention. Suitable nucleating agents which may be employed includecalcium salts such as calcium terephthalate, calcium titanate, calciumpyrophosphate, calcium silicate, calcium benzoate, calcium oxide,calcium carbonate, calcium fluoride and the like; sodium silicate andsodium phenyl phosphenate and zeolites such as sodium aluminosilicate,calcium aluminosilicate, hydrous aluminosilicate and the like and zincborate. In addition, certain materials which are ordinarily used asfillers such as the mineral silicates, talc, clay, silica and mica mayalso act as nucleating agents. The preferred nucleating agents are thecalcium salts and of these calcium silicate is especially preferred.

Amounts of nucleating agent which may be present in the composition canrange from about 0.1 to about 5.0 parts by weight per 100 parts byweight of total composition. Preferred amounts range from 0.5 to 3.0parts by weight per 100 parts by weight of total composition.

Any of the reinforcing and filler materials heretofore utilized inpreparing polyethylene terephthalate molding compositions may beemployed in the compositions of the invention. The preferred reinforcingmaterial is glass fibers. Filler materials which may be employed includemica, clay, talc and vermiculite. It is often desirable to use a mixtureof reinforcing material and filler such as a mixture of glass fibers andmica.

Amounts of reinforcing material or mixture of reinforcing material andfiller which may be present in the composition can range from about 20to about 60 parts by weight per 100 parts by weight of totalcomposition. Preferred amounts range from 25 to 50 parts by weight per100 parts by weight of total composition.

As indicated, the compositions of the invention also contain a molecularweight reducing agent for the polyethylene terephthalate resin. This isan extremely important aspect of the compositions of the invention.Thus, the addition of a molecular weight reducing agent to thecompositions of the invention provides a means for readily controllingthe molecular weight of the polyethylene terephthalate in order toobtain the optimum molecular weight required for excellent moldingcharacteristics. Molecular weight reducing agents which may be utilizedin the composition include benzoic acid, neopentyl glycol and water. Thepreferred molecular weight reducing agent is benzoic acid.

The amounts of molecular weight reducing agent to be utilized in thecompositions is in general dependent upon the intrinsic viscosity of theoriginal polyethylene terephthalate resin. In general, the amount ofmolecular weight reducing agent added to the composition should besufficient to achieve an intrinsic viscosity in the molded polyethyleneterephthalate composition of from about 0.48 to about 0.52 dl/g asmeasured at 25° C. in a 1:1 phenol/tetrachloroethane solution. Suitableamounts of molecular weight reducing agent employed in the compositionmay range from about 0.01 to about 1.0 parts by weight per 100 parts byweight of total composition. Preferred amounts range from 0.01 to 0.5parts by weight of total composition.

In addition to the above components, the compositions of the inventionmay contain other special purpose additives such as antioxidants,ultraviolet absorbers, antistatic agents, flame retardants, dyes,pigments (e.g., carbon black, titanium dioxide, etc.) and other fillersconventionally employed in molding compositions. The flame retardantsmay be of the metallic compound type (e.g., antimony trioxide, zincmolybdate, zinc oxide, zinc borate, clay, talc, mica, etc.) or thehalogenated compound type (e.g., decabromophenylether,ethylene-bis-3,4,5,6-tetrabromophthalimide, etc.) or mixtures thereof. Apreferred flame retardant mixture is a mixture of zinc borate anddecabromophenylether or ethylene-bis-3,4,5,6-tetrabromophthalimide.

In instances where other known fillers are to be included in thecomposition of the invention, these may be utilized in amounts of fromabout 20 to about 50 parts by weight per 100 parts by weight of totalcomposition. In instances where it is desired to include metalliccompound flame retardants in the composition, these may be utilized inamounts of from about 0.2 to about 8 parts by weight per 100 parts byweight of total composition. In instances where it is desired to includehalogenated compound flame retardants in the composition, these may beutilized in amounts of from about 6 to about 16 parts by weight per 100parts by weight of total composition. The preferred flame retardantmixture can be utilized in amounts of from about 8 to about 14 parts byweight of decabromophenylether orethylene-bis-3,4,5,6-tetrabromophthalimide and from about 0.2 to about 6parts by weight of zinc borate per 100 parts by weight of totalcomposition.

The compositions of the invention can be prepared and molded using anyconventional or well known method. The preferred method which isemployed in a number of the examples herein involves melt blending thecomposition components in a twin screw extruder, chopping the extrudedcomposition into pellets and then injection molding the pelletedcomposition into a conventional injection mold having a mold temperatureof 100° C. or less.

Another method which is employed in a number of the examples hereininvolves melt blending the composition components in a BrabenderPlasticorder and then transfer molding the blended compositions. Thismethod has several disadvantages which limits its usefulness. Thus, onlysmall quantities of composition can be prepared and molded using themethod. Moreover, the ultimate strength values of molded compositionsprepared by the method are generally about 50% less than those preparedby the preferred method. Nevertheless, this method has value as ascreening procedure for evaluating compositional variations,particularly if the effect of the method on ultimate strength propertiesis kept in mind. Additionally, it has been found that the energy atbreak values of molded compositions prepared by this method can beutilized in many cases to determine whether the compositions wouldexhibit acceptable strength properties if prepared and molded by thepreferred method. Thus, it has been found that in most instances ifmolded compositions prepared by the method approach or exceed 100 psi,the composition will exhibit acceptable strength values when preparedand molded by the preferred method.

The following examples are submitted for the purpose of furtherillustrating the nature of the present invention and are not intended asa limitation on the scope thereof. Parts and percentages referred to inthe examples are by weight unless otherwise indicated.

EXAMPLES 1-28

These examples illustrate compositions of the invention prepared andmolded using the screening procedure referred to above. In theseexamples, the compositions were prepared by melt blending thepolyethylene terephthalate (hereinafter PET) and other components in aBrabender Plasticorder for 10 minutes following which the blendedcompositions were transfer molded in a Carver press. The moldedcompositions were then tested for various properties. Compositionformulations and test results are shown in Tables I-VI.

                  TABLE I                                                         ______________________________________                                        Example No.  1       2       3     4     5                                    ______________________________________                                        Ingredients                                                                   PET.sup.(a)  62.12   62.12   62.12 62.12 62.12                                Surlyn 1559.sup.(b)                                                                        5.12    3.50    --    3.50  3.50                                 Styron.sup.(c)                                                                             --      --      3.50  --    --                                   Neopentyl glycol                                                                           2.35    --      2.40  2.40  2.40                                 dibenzoate.sup.(d)                                                            Trixylyl phosphate.sup.(d)                                                                 --      2.40    --    --    --                                   Calcium fluoride.sup.(e)                                                                   2.01    --      --    --    --                                   Calcium phosphate.sup.(e)                                                                  --      --      --    1.79  --                                   Calcium silicate.sup.(e)                                                                   --      1.79    1.79  --    1.79                                 Benzoic acid.sup.(f)                                                                       0.26    0.26    0.26  0.26  --                                   Neopentyl glycol.sup.(f)                                                                   --      --      --    --    0.22                                 Chopped glass fibers                                                                       28.40   29.93   29.93 29.93 29.97                                (1/4" fibers)                                                                              100.26  100.00  100.00                                                                              100.00                                                                              100.00                               Properties                                                                    Flex strength × 10.sup.-3,                                                           17.4    16.4    16.2  14.8  18.3                                 psi                                                                           Flex modulus × 10.sup.-6,                                                            0.93    0.95    1.11  1.01  0.94                                 psi                                                                           Max. strain, %                                                                             2.05    1.88    1.55  1.63  2.21                                 Energy at break, psi                                                                       181     161     128   123   209                                  Molded viscosity                                                                           0.55    0.63    0.60  0.61  0.58                                 (I.V.), dl/g                                                                  ______________________________________                                         .sup.(a) intrinsic viscosity (I.V.) = 0.94 dl/g                               .sup.(b) sodium ionomer of polyethylene and methacrylic acid available        from duPont Company                                                           .sup.(c) a polystyrene homopolymer available from Dow Chemical Company        .sup.(d) plasticizer                                                          .sup.(e) nucleating agent                                                     .sup.(f) molecular weight reducing agent for PET                         

                  TABLE II                                                        ______________________________________                                        Example No.  6       7       8     9     10                                   ______________________________________                                        Ingredients                                                                   PET.sup.(a)  62.12   62.12   63.76 63.76 63.76                                Polyethylene (2%                                                                           3.50    --      --    --    --                                   epoxy).sup.(b)                                                                Polyethylene (7%                                                                           --      3.50    --    --    --                                   epoxy).sup.(c)                                                                Surlyn 1559  --      --      3.54  3.54  3.54                                 Neopentyl glycol                                                                           2.40    2.40    2.44  2.44  2.44                                 dibenzoate                                                                    Calcium silicate                                                                           1.79    1.79    --    --    --                                   Mica         --      --      1.80  --    --                                   Zeolite.sup.(d)                                                                            --      --      --    1.80  --                                   Kaolin clay  --      --      --    --    1.80                                 Benzoic acid 0.21    0.21    0.26  0.26  0.26                                 Chopped glass fibers                                                                       29.98   29.98   28.20 28.20 28.20                                             100.00  100.00  100.00                                                                              100.00                                                                              100.00                               Properties                                                                    Flex strength × 10.sup.-3,                                                           16.6    14.1    16.6  16.7  20.9                                 psi                                                                           Flex modulus × 10.sup.-6,                                                            0.97    0.88    1.29  1.22  1.26                                 psi                                                                           Max. strain, %                                                                             1.90    1.78    1.38  1.45  1.77                                 Energy at break, psi                                                                       160     130     121   123   188                                  Molded viscosity                                                                           0.56    0.60    0.50  0.52  0.55                                 (I.V.), dl/g                                                                  ______________________________________                                         .sup.(a) I.V. = 0.93 to 0.94 dl/g                                             .sup.(b) polyethylene containing 2% epoxy groups available from Sumitomo      Chemical Company                                                              .sup.(c) polyethylene containing 7% epoxy groups available from Sumitomo      Chemical Company                                                              .sup.(d) calcium aluminosilicate                                         

                  TABLE III                                                       ______________________________________                                        Example No.  11      12      13    14     15                                  ______________________________________                                        Ingredients                                                                   PET.sup.(a)  63.76   63.76   63.76 62.12 62.12                                Surlyn 1559  3.54    3.54    --    3.48  3.48                                 Surlyn 1554.sup.(b)                                                                        --      --      3.54  --    --                                   Neopentyl glycol                                                                           2.44    2.44    2.44  --    --                                   dibenzoate                                                                    Butyl benzyl --      --      --    2.40  --                                   phthalate                                                                     Dioctyl phthalate                                                                          --      --      --    --    2.40                                 Fumed silica 1.80    --      --    --    --                                   Vermiculite  --      1.80    --    --    --                                   Calcium silicate                                                                           --      --      1.80  --    --                                   Sodium silicate                                                                            --      --      0.18  --    --                                   Calcium phosphate                                                                          --      --      --    0.38  0.38                                 Calcium fluoride                                                                           --      --      --    1.47  1.47                                 Benzoic acid 0.26    0.26    0.08  0.13  0.26                                 Chopped glass fibers                                                                        28.20  28.20   28.20 30.02 29.89                                             100.00  100.00  100.00                                                                              100.00                                                                              100.00                               Properties                                                                    Flex strength × 10.sup. -3,                                                          17.0    19.5    16.9  12.8  14.0                                 psi                                                                           Flex modulus × 10.sup.-6,                                                            1.19    1.19    1.07  1.02  1.13                                 psi                                                                           Max. strain, %                                                                             1.51    1.79    1.75  1.52  1.37                                 Energy at break, psi                                                                       133     182     149   103   101                                  Mold viscosity                                                                             0.54    0.54    0.59  0.46  0.44                                 (I.V.), dl/g                                                                  ______________________________________                                         .sup.(a) I.V. of PET for Examples 11-13 is 0.93 dl/g,; for Example 14 is      0.59 dl/g and for Example 15 is 0.94 dl/g                                     .sup.(b) zinc ionomer of polyethylene and methacrylic acid available from     duPont Company                                                           

                  TABLE IV                                                        ______________________________________                                        Example No.  16      17      18    19    20                                   ______________________________________                                        Ingredients                                                                   PET.sup.(a)  55.70   62.12   62.30 62.12 62.12                                EPDM.sup.(b) 9.87    3.50    --    --    --                                   EPDM/MA.sup.(c)                                                                            --      --      3.50  --    --                                   Surlyn 1559  --      --      --    3.48  3.50                                 Neopentyl glycol                                                                           2.40    --      2.40  2.40  2.40                                 dibenzoate                                                                    Pentaerythritol                                                                            --      2.40    --    --    --                                   tetrabenzoate                                                                 NYAD-G.sup.(d)                                                                             1.79    1.88    1.80  --    --                                   Calcium carbonate                                                                          --      --      --    1.74  --                                   Zinc borate  --      --      --    --    1.79                                 Benzoic acid 0.21    0.26    0.20  0.26  --                                   Water        --      --      --    --    0.03                                 Chopped glass fibers                                                                       28.89   30.00   30.00 30.00 30.19                                             99.86   100.16  100.20                                                                              100.00                                                                              100.03                               Properties                                                                    Flex strength × 10.sup.-3,                                                           5.30    11.50   18.70 14.60 15.60                                psi                                                                           Flex modulus × 10.sup.-6,                                                            0.66    1.06    1.25  0.82  1.04                                 psi                                                                           Max. strain, %                                                                             1.00    1.33    1.69  1.91  1.66                                 Energy at break, psi                                                                       30*     81      165   139   133                                  Notched Izod, 1/4"                                                                         --      --      1.31  --    --                                   bar, ft.lbs./in.                                                              Molded viscosity                                                                           --      0.38    0.36  0.65  0.60                                 (I.V.), dl/g                                                                  ______________________________________                                         .sup.(a) I.V. of PET for Examples 16 and 18 is 0.93 dl/g, For Example 17      is 0.71 dl/g and for Example 19 and 20 is 0.94 dl/g.                          .sup.(b) an ethylene/propylene diene monomer terpolymer available from        duPont Company under the designation Nordel                                   .sup.(c) a maleic anhydride adduct of the EPDM terpolymer containing 0.53     by weight of maleic anhydride                                                 .sup.(d) calcium silicate                                                     *low energy at break value believed due to very low molded viscosity (not     measured) caused by combination of high EPDM level and excessive water        absorption. Note Example 17 having higher energy at break value. If the       compositions were prepared by preferred process, it is believed that the      value would be much higher and acceptable.                               

                  TABLE V                                                         ______________________________________                                        Example No.  21        22       23     24                                     ______________________________________                                        Ingredients                                                                   PET.sup.(a)  45.67     45.67    59.43  59.43                                  Surlyn 1559  2.54      2.54     2.11   2.11                                   Neopentyl glycol dibenzoate                                                                1.76      1.76     1.45   1.45                                   Calcium silicate                                                                           1.29      --       --     --                                     Talc         --        1.29     --     --                                     Mica         --        --       10.00  10.00                                  Benzoic acid --        --       0.08   0.08                                   Water        0.03      0.03     --     --                                     Chopped glass fibers                                                                       48.74     48.74    25.00  23.20                                               100.03    100.03   98.07  96.27                                  Properties                                                                    Flex strength × 10.sup.-3,                                                           22.4      22.5     15.9   19.6                                   psi                                                                           Flex modulus × 10.sup.-6,                                                            1.61      1.63     1.14   1.25                                   psi                                                                           Max. strain, %                                                                             1.67      1.65     1.53   1.86                                   Energy at break, psi                                                                       199       196      126    199                                    Molded viscosity (I.V.),                                                                   0.53      0.60     0.57   0.50                                   dl/g                                                                          ______________________________________                                         .sup.(a) I.V. = 0.93 dl/g                                                

Examples 25-28 in Table VI illustrate flame retardant compositions ofthe invention.

                  TABLE VI                                                        ______________________________________                                        Example No.  25       26       27     28                                      ______________________________________                                        Ingredients                                                                   PET.sup.(a)  54.20    54.20    54.20  54.20                                   Surlyn 1559  3.01     3.01     3.01   3.01                                    Neopentyl glycol                                                                           1.32     1.32     1.32   1.32                                    dibenzoate                                                                    Zinc borate  3.18     3.18     1.66   1.66                                    Calcium silicate                                                                           --       --       1.52   1.52                                    Decabromophenylether                                                                       9.56     --       9.56   --                                      Ethylene-bis-3,4,5,6-                                                                      --       9.56     --     9.56                                    tetra-                                                                        bromophthalimide                                                              Water        0.03     0.03     0.03   0.03                                    Chopped glass fibers                                                                       28.73    28.73    28.73  28.73                                                100.03   100.03   100.03 100.03                                  Properties                                                                    Flex strength × 10.sup.-3, psi                                                       16.4     12.96    20.06  18.16                                   Flex modulus × 10.sup.-6, psi                                                        1.17     0.90     1.05   1.14                                    Energy at break                                                                            128      96       190    158                                     Molded viscosity (I.V.),                                                                   0.50     0.64     0.69   0.57                                    dl/g                                                                          LOI.sup.(b)  31.0     --       30.0   --                                      UL 94, 1/8"  0        0        0      0                                       ______________________________________                                         .sup.(a) I.V. = 0.93 dl/g                                                     .sup.(b) Limiting Oxygen Index                                           

EXAMPLES 29-38

These examples illustrate compositions of the invention prepared andmolded using the preferred procedure described above. In these examples,the compositions were prepared by melt blending the compositioncomponents in a Werner-Pfliederer ZSK53 twin screw extruder at 290° C.and then chopping the extrudate into pellets. The pellets were theninjection molded into a Cincinnati Milicron molder having a moldtemperature of 60°-90° C. The molded compositions were then tested forvarious properties. Composition formulations and test results are shownin Tables VII and VIII.

                  TABLE VII                                                       ______________________________________                                        Example No.  29      30      31    26.2  33                                   ______________________________________                                        Ingredients                                                                   PET.sup.(a)  62.30   62.10   62.30 62.30 62.30                                Surlyn 1559  3.50    3.50    3.50  3.50  3.50                                 Neopentyl glycol di-                                                                       2.40    2.40    2.40  2.40  2.40                                 benzoate                                                                      Calcium silicate                                                                           1.80    1.80    --    --    --                                   Calcium fluoride                                                                           --      --      1.80  --    1.80                                 Mica         --      --      --    1.80  --                                   Benzoic acid --      0.20    --    --    --                                   Water        0.03    --      0.04  0.04  0.04                                 Chopped glass fibers*                                                                      30.00   30.00   30.00 30.00 30.00                                             100.03  100.00  100.04                                                                              100.04                                                                              100.04                               Properties                                                                    Flex strength × 10.sup.-3,                                                           32.7    34.3    28.6  36.4  27.0                                 psi                                                                           Flex modulus × 10.sup.-6,                                                            1.44    1.58    1.55  1.53  1.25                                 psi                                                                           Tensile strength ×                                                                   23.8    25.2    22.7  26.2  19.3                                 10.sup.-3, psi                                                                Tensile % elongation                                                                       1.98    1.78    2.00  2.13  1.82                                 Energy at break, psi                                                                       365     324     280   416   260                                  Notched Izod, 1/4" bar,                                                                    1.54    1.76    1.57  1.63  1.24                                 ft.lbs./in.                                                                   Heat distortion temp.                                                                      233     237     232   237   230                                  °C. at 264 psi                                                         Molded viscosity                                                                           0.54    0.49    0.50  0.46  0.49                                 (I.V.), dl/g                                                                  ______________________________________                                         .sup.(a) I.V. = 0.91 dl/g                                                     *Examples 29 through 32 contain PPG 3540 1/4" fibers, Example 33 contains     PPG 3080 1/4" fibers.                                                    

                  TABLE VIII                                                      ______________________________________                                        Example No.  34      35      36    37    38                                   ______________________________________                                        Ingredients                                                                   PET.sup.(a)  62.30   62.30   62.30 62.30 62.30                                Surlyn 1559  3.50    3.50    3.50  3.50  3.50                                 Neopentyl glycol di-                                                                       2.40    2.40    2.40  2.40  --                                   benzoate                                                                      Glycerol tribenzoate                                                                       --      --      --    --    2.4                                  Calcium fluoride                                                                           1.80    --      --    --    1.80                                 Talc (8 μm)                                                                             --      1.80    --    --    --                                   Talc (3 μm)                                                                             --      --      1.80  --    --                                   Kaolin clay  --      --      --    1.80  --                                   Water        0.04    0.04    0.04  0.04  0.04                                 Chopped glass fibers*                                                                      30.00   30.00   30.00 30.00 30.00                                             100.04  100.04  100.04                                                                              100.04                                                                              100.04                               Properties                                                                    Flex strength × 10.sup.-3,                                                           30.8    34.6    36.2  28.9  29.5                                 psi                                                                           Flex modulus × 10.sup.-6,                                                            1.47    1.43    1.43  1.34  1.43                                 psi                                                                           Tensile strength ×                                                                   23.1    25.1    26.2  22.0  16.3                                 10.sup.-3, psi                                                                Tensile % elongation                                                                       1.83    2.08    2.38  1.80  1.67                                 Energy at break, psi                                                                       285     380     416   273   209                                  Notched Izod, 1/4"                                                                         1.39    1.60    1.65  1.09  1.29                                 bar, ft.lbs./in.                                                              Heat distortion temp.                                                                      237     232     --    --    231                                  °C. at 264 psi                                                         Molded viscosity                                                                           0.46    0.50    0.51  0.51  0.44                                 (I.V.), dl/g                                                                  ______________________________________                                         .sup.(a) I.V. = 0.91 dl/g                                                     *Example 34 contains Owens Corning Glass 419 1/4" fiber and Examples 35       through 38 contain PPG 3540 1/4" fiber.                                  

We claim:
 1. Polyethylene terphthalate molding compositions which can bemolded at temperatures of 100° C. or less comprising:(a) from about 40to about 70 parts by weight per 100 parts of total composition of apolyethylene terephthalate having an intrinsic viscosity of 0.4 to 1.0dl/g as measured at 25° C. in a 1:1 mixture of phenol andtetrachloroethane; (b) from about 0.5 to about 5.0 parts by weight per100 parts by weight of total composition of a plasticizer selected fromthe group consisting of dioctyl phthalate, butyl benzyl phthalate andphosphate esters; (c) from about 0.5 to about 10.0 parts by weight per100 parts by weight of total composition of a lubricating polymer; (d)from about 0.1 to about 5.0 parts by weight per 100 parts by weight oftotal composition of a nucleating agent; (e) from about 20 to about 60parts by weight per 100 parts by weight of total composition of areinforcing material or mixture of reinforcing material and filler; and(f) from about 0.01 to about 1.0 parts by weight per 100 parts by weightof total composition of a molecular weight reducing agent for saidpolyethylene terephthalate, wherein said molecular weight reducing agentis selected from the group consisting of neopentyl glycol and water. 2.The composition of claim 1 wherein said phosphate ester is trixylylphosphate.
 3. The composition of claim 1 wherein said lubricatingpolymer is polystyrene.
 4. The composition of claim 1 wherein saidlubricating polymer is a polyethylene containing 2% epoxy groups or apolyethylene containing 7% epoxy groups.
 5. The composition of claim 1wherein said lubricating polymer is an ethylene/propylene/diene monomerterpolymer.
 6. The composition of claim 1 wherein said lubricatingpolymer is a maleic anhydride adduct of an ethylene/propylene/dienemonomer terpolymer.
 7. The composition of claim 1 wherein saidnucleating agent is zinc borate.
 8. The composition of claim 1 whereinsaid filler material is mica, talc, clay or vermiculite.
 9. Thecomposition of claim 1 further comprising flame retardant additivesselected from the group consisting of metallic compounds, halogenatedcompounds and mixtures thereof.
 10. The composition of claim 9 whereinthe flame retardant additive is a mixture of zinc borate anddecabromophenylether or ethylene-bis-3,4,5,6-tetrabromophthalimide. 11.The composition of claim 10 containing from about 0.2 to about 6 partsby weight of zinc borate and from about 8 to about 14 parts by weight ofdecabromophenylether or ethylene-bis-3,4,5,6-tetrabromophthalimide.